As an Oct. 26 deadline to finish the prototype border-wall designs drew near, The Arizona Republic toured the construction site a few-dozen yards from the border that divides this city from neighboring Tijuana, Mexico.

U.S. Customs and Border Protection awarded eight contracts to six companies to build the prototypes. Four are made of reinforced concrete, and another four incorporate additional construction materials. Construction began on Sept. 26, giving companies 30 days to finish.

By Tuesday afternoon, when CBP allowed The Republic access to the site, five of the wall designs had already been completed and were fenced off with caution tape.

But crews were still at work on others, installing vertical concrete panels on one design, using cranes and bulldozers to place them upright. Another two prototypes were in various stages of construction.

The construction site is about 2 miles east of San Diego's Otay Mesa border crossing, in the foothills of the Otay Mountains.

At 30 feet, the designs dwarf the primary fence that currently marks the international boundary — it's made of rusted Vietnam War-era landing mats. They are nearly twice the height of the secondary metal-mesh fence, which ends near where the prototypes are being built.

Their height, officials said, is intended to make a statement to criminals and would-be unauthorized crossers: Stay away.

"The 30 feet is very impressive," said Mario Villareal, the division chief for the San Diego Sector Border Patrol. "What we're trying to accomplish is by putting tactical infrastructure on the border, by having all-weather roads, by putting Border Patrol agents on the immediate border is the deterrence."

Whether the border-wall prototypes keep people away will be closely scrutinized in the coming weeks. After they are done, CBP will move to the "test and evaluation" of each of the eight structures.